With the development of digitization of a communication line and character input/output technique such as word processing, realization of communication apparatus which allows mutual conversion between the characters and voices has been demanded. One approach thereto is described in Japanese Patent Publication No. 59-19358 entitled "Voice Transmission System" coinvented by one of inventors of the present invention. In the disclosed system, a telex machine is combined with a voice typewriter and speech synthesis by rule. However, it is a strong demand in the voice transmission to communicate the personal tone of a speaker. In the disclosed system, it is difficult to realize the character communication. On the other hand, with the development of the word processing technique, a system which uses a word processor as a communication terminal and an integrated voice data terminal (IVDT) which combines a telephone with the communication terminal have been proposed. However, although the voice and character data are incorporated in one terminal, information thereof is independently handled and organic coupling of the information is not attained.